#!/bin/bash


#########color code#############
RED="31m"      # Error message
GREEN="32m"    # Success message
YELLOW="33m"   # Warning message
BLUE="36m"     # Info message

sshConfigFile="/etc/ssh/sshd_config"

## 下面的应该被改成yes
PermitRootLogin="PermitRootLogin"
PasswordAuthentication="PasswordAuthentication"
tcpKeepAlive="TCPKeepAlive"

## 下面的应该被改成no
changeResponseAuthentication="ChallengeResponseAuthentication"
PermitEmptyPasswords="PermitEmptyPasswords"
StrictModes="StrictModes"

###############color echo func#################
colorEcho(){
    echo -e "\033[${1}${@:2}\033[0m" 1>& 2
}

check_root(){
	if [[ $EUID != 0 ]];then
    colorEcho ${RED} "当前非root账号(或没有root权限)，无法继续操作，请更换root账号!"
    colorEcho ${YELLOW} "使用sudo -命令获取临时root权限（执行后可能会提示输入root密码）"
    exit 1
    fi
}

back_up_config(){
    cp $sshConfigFile $sshConfigFile.backup
}

modify_sshd_config_yes(){
    numOfElements=$#
   
    while [ $# -gt 0 ] 
    do
        if grep -x "$1 yes" $sshConfigFile
        then
            shift
        elif grep -x "#$1 yes" $sshConfigFile 
        then
            sed -i "s/#$1 yes/$1 yes/g" $sshConfigFile
            shift
        elif grep -x "$1 no" $sshConfigFile
        then
            sed -i "s/$1 no/$1 yes/g" $sshConfigFile
            shift
  
        else
            sed -i "$ a $1 yes" $sshConfigFile
            shift
        fi      
    done
}

modify_sshd_config_no(){
    numOfElements=$#
   
    while [ $# -gt 0 ]
    do
        if grep -x "$1 no" $sshConfigFile
        then
            shift
        elif grep -x "#$1 no" $sshConfigFile 
        then
            sed -i "s/#$1 no/$1 no/g" $sshConfigFile
            shift
        elif grep -x "$1 yes" $sshConfigFile
        then
            sed -i "s/$1 yes/$1 no/g" $sshConfigFile
            shift
        else
            sed -i "$ a $1 no" $sshConfigFile
            shift
        fi
    done
}


main(){
    # 首先检查是否拥有root权限
    check_root
    # 备份一份sshd的配置文件
    back_up_config

    declare -a needToChangeYes
    declare -a needToChangeNo

    needToChangeYes[0]=$tcpKeepAlive 
    needToChangeYes[1]=$PermitRootLogin
    needToChangeYes[2]=$PasswordAuthentication 

    needToChangeNo[0]=$PermitEmptyPasswords
    needToChangeNo[1]=$changeResponseAuthentication

    #  以数组的方式 将参数传入函数
    modify_sshd_config_yes "${needToChangeYes[@]}"
    modify_sshd_config_no "${needToChangeNo[@]}"
    
    systemctl restart sshd.service
    if [ $? ];then 
        echo "sshd文件已经修改成功，可以进行root登录，请修改root密码！！"
    else 
        echo "sshd服务重启失败，请检查原因"
    fi
}

main